Improve readme with build instructions

## :beers: SCALE Public Repository :beers:

# :beers: SCALE Public Repository :beers:

Welcome to the SCALE (scale.ornl.gov) public repository. The current content

is a very a sparse snapshot of the open source components in **SCALE 7.0 beta3**

:warning: This snapshot is very experimental and subject to change. :warning:

----

## Build Instructions

### Build Prerequisites

 - git-lfs

 - C++ compiler: gcc, clang, etc. 

 - Fortran compiler: gfortran, etc.

 - hdf5 - 1.10

 - Qt5 <!-- UNTIL the next SCALE beta is pulled in here -->

### Full SCALE-public Build

To build the full SCALE-public toolset, it's recommended to install with `spack`. When building with `spack`, the main difference, **for now**, betweeen building AMPX and full SCALE-public are the build options given by CMake flags during configuration of SCALE.

### AMPX Build

There are two ways to build the AMPX toolset: with `spack` or without `spack`. Either way, start by cloning the repository:

```console

git clone https://code.ornl.gov/scale/code/scale-public.git

```

**Caveat that applies to both build methods**: Unit tests are disabled because some tests depend on packages in the full SCALE source that are not included in the public release.  

<p>

<h3>Build without spack</h3>

<details>

<summary>Details</summary>

Both the `spack` and non-`spack` builds require Trilinos. When building without `spack` you must download and build Trilinos on your own before you can build AMPX. Usually this is not a big issue.

<details>

<summary>Build Trilinos</summary>

```

git clone https://github.com/trilinos/Trilinos.git

mkdir build_trilinos

cd build_trilinos

<launch configuration script for Trilinos below>

make -j 4 install 

cd ..

```

Configuration script for Trilinos: 

```

cmake  \

-D CMAKE_Fortran_FLAGS="-fallow-argument-mismatch -fallow-invalid-boz" \

-D CMAKE_INSTALL_PREFIX:FILEPATH=${INSTALL_PATH} \

-DTrilinos_ENABLE_ALL_PACKAGES=OFF \

-DTPL_ENABLE_Boost=OFF \

-DTPL_ENABLE_Netcdf=OFF \

-DTrilinos_ENABLE_KokkosCore=ON \

-DTrilinos_ENABLE_TeuchosComm=ON \

-DTrilinos_ENABLE_TeuchosParameterList=ON \

-DTrilinos_ENABLE_TeuchosNumerics=ON \

-DTrilinos_ENABLE_Tpetra=ON \

-DTrilinos_ENABLE_Amesos2=ON \

-DTrilinos_ENABLE_Anasazi=ON \

-DTrilinos_ENABLE_Shards=ON \

-DTrilinos_ENABLE_Intrepid=ON \

-DTrilinos_ENABLE_Ifpack2=ON \

-DTrilinos_ENABLE_Stratimikos=ON \

-DBUILD_SHARED_LIBS=ON \

$*

```

</details>

Once Trilinos is built, we can build SCALE (assuming you have the other dependencies required):

```

mkdir build

cd build

<launch configuration script for SCALE below>

make -j 4 install

```

Configuration script for AMPX: 

```

cmake \

-DCMAKE_PREFIX_PATH=/path/to/trilinos/installation \

-DSCALE_USE_MCNP=OFF \

-DSCALE_USE_MPI=OFF \

-DSCALE_DEBUG=OFF \

-DSCALE_BUILD_TESTS=OFF \

-DSCALE_USE_SWIG_Python:BOOL=OFF \

-DSCALE_USE_SWIG_Fortran:BOOL=OFF \

-DCMAKE_INSTALL_PREFIX=${INSTALL_PATH} \

-DCMAKE_BUILD_TYPE=RELEASE \

$*

```

**Warning**: When running AMPX executables, this build procedure requires setting 

```bash

export LD_LIBRARY_PATH="/path/to/trilinos/installation/lib:$LD_LIBRARY_PATH"

```

at runtime.  

</details>

</p>

<p>

<h3>Build with spack</h3>

<details>

<summary>Details</summary>

To build with `spack`, first ensure you have `spack` installed. Next create a build directory and a script directory in the main `scale-public` repo:

```console

cd ~/scale-public

mkdir build

mkdir myscript

```

Next create a YAML file called `w2022.yaml` in your `myscript` directory to describe your `spack` environment and paste the following content in it:

```console

# This is the w2022-mac.yaml Spack Environment file 

spack:

  # add package specs to the `specs` list

  specs:

  - celeritas@0.1.0 cxxstd=14

  - bison@3.4.2

  - flex@2.6.4

  - 'flibcpp@1.0.1: +swig'

  - hdf5 +fortran +hl ~mpi

  - lava

  - googletest

  - gnds

  - 'ninja@1.10:'

  - nlohmann-json

  - openblas

  - openmpi@:2.999

  - pugixml

  - python +uuid

  - py-h5py@:2 ~mpi   # compound vlen bug in 2.6-3.1 and 3.3+

  - py-lxml

  - py-jsonschema

  - py-matplotlib

  - py-numpy

  - py-pandas

  - py-pint

  - py-psutil

  - py-pyyaml

  - py-sphinx

  - py-tqdm

  - silo +fortran ~mpi

  - swig@4.0.2-fortran

  - 'superlu@5:'

  - trilinos +amesos +amesos2 +anasazi +aztec +belos +ifpack gotype=long_long +epetra

    +epetraext +kokkos +ifpack2 +intrepid +ml +sacado +shards +tpetra +stratimikos

    ~mpi

  view: true

  concretizer:

    unify: true

  packages:

    celeritas:

      variants: ~geant4 ~hepmc3 ~root ~vecgeom

    hdf5:

      version: [1.10.8] # needed for h5py@2 

    hwloc:

      version: [1.11.13] # needed for openmpi 2

    qt:

      variants: ~dbus~examples~gtk~opengl~phonon+shared~sql~ssl~tools~webkit

    superlu:

      version: [5.2.2]

    trilinos:

      variants: ~adios2 ~alloptpkgs ~boost ~cgns ~chaco ~complex ~debug ~dtk ~exodus

        +explicit_template_instantiation ~float +fortran ~fortrilinos ~glm   ~gtest

        ~hdf5 ~hypre  ~intrepid2 ~isorropia ~matio ~mesquite ~metis ~minitensor ~muelu

        ~mumps ~netcdf ~nox ~openmp ~phalanx ~piro ~pnetcdf ~python ~rol ~rythmos

        +shared ~shylu ~stk ~suite-sparse ~superlu ~superlu-dist ~teko ~tempus ~x11

        ~zlib ~zoltan ~zoltan2

    all:

      providers:

        blas: [openblas]

        lapack: [openblas]

        mpi: [openmpi]

```

Following that source the environment, create and activate an environment based on the YAML file in the `scale-public` repo:

```console

. ~/spack/share/spack/setup-env.sh

spack env create w2022 w2022.yaml

spack env activate w2022

```

Then we are ready to build and compile the `spack` environment, which can take over an hour:

```console

spack concretize

spack install -j16

```

Often we've found that having Qt installed from a non-`spack` source works best, I choose `brew`:

```console

brew install qt@5

```

Next create a configuration script file called `configure-ampx.sh` in the `myscript` directory with the following inside:

```console

#!/bin/bash -x

INSTALL_PATH=${PWD}/install

#remove existing CMakeCache if it exists

if [ -e CMakeCache.txt ] ; then

   rm -v CMakeCache.txt 

   rm -fr CMakeFiles

fi

spack env activate w2022

export PATH=/usr/local/Cellar/qt@5/5.15.7/bin:$PATH

cmake \

-GNinja \

-DSCALE_USE_MCNP=OFF \

-DSCALE_USE_MPI=OFF \

-DSCALE_DEBUG=OFF \

-DSCALE_BUILD_TESTS=OFF \

-DSCALE_USE_SWIG_Python:BOOL=OFF \

-DSCALE_USE_SWIG_Fortran:BOOL=OFF \

-DCMAKE_INSTALL_PREFIX=${INSTALL_PATH} \

-DCMAKE_BUILD_TYPE=RELEASE \

$*

```

Then make and install:

```console

ninja -j16

```

</details>

</p>